This invention relates to a thermal actuator for producing a controlled displacement of a movable member in response to temperature changes.
Many applications exist for devices which provide a controlled temperature dependent movement of a mechanical member. A thermostatic switch is one example. Another example would be a temperature compensated valve. It is well-known to construct such devices using elements formed out of thermostatic bimetallic material. However, in many such cases, the bimetallic material must be formed into complicated shapes, such as coils or helixes. In other cases, the type of temperature responsive motion provided is limited in complexity. For example, the known devices do not provide for movement to displaced position over a certain temperature range and movement to a retracted position at temperatures both above and below that temperature range. Similarly, the known devices do not provide for multiple step-wise temperature responsive movement. It would be desirable to provide thermal actuators with such temperature responsive movements using low-cost, conventional and easily obtainable thermostatic elements.